For any pianist looking for a piano that has superior touch and tone, so as to be able to perform high level works, or perhaps moderate level works with greater ease and enjoyment, purchasing a grand piano of at least 6′ in length has been the requirement, as these pianos have the length of string, and soundboard area sufficient to produce excellent tone. They also have a high response action mechanism. This responsiveness is enabled by a repetition lever, and the force of gravity on the hammers, which in a grand piano travel vertically to strike strings which are oriented horizontally.
Most musicians have neither the space nor the money to afford such an instrument. The next best option currently available is to purchase a tall upright piano because of its long string length and large soundboard size, however because the strings of this type of piano are oriented vertically, the hammers must travel horizontally, and be a significant distance above the keys in order to strike the strings in the correct location, often necessitating additional parts to span the gap between the key and wippen. One downside to the common upright action, is that to reset the action so that it can be struck again, it relies on the parts below the hammer butt to move back into position faster than the hammer does. For this reason, there is often a difference between the movement of the hammer and butt, and the lower parts of the action, causing unpredictability when playing difficult passages. In addition, because there is little spring force and dead weight pushing the keys back up from the fully depressed position, (compared to a grand piano action), the pianist must lift more on their fingers when playing quickly. To date, none have been very successful in producing vertical pianos that could solve these problems without high cost of production, or problems with serviceability.